1. Field of the Invention
This invention relates to vertical and/or take-off and landing (V/STOL) aircraft.
2. Discussion of Prior Art
There are many designs of V/STOL aircraft such as the Harrier in which the thrust generated by the aircraft powerplant is exhausted through nozzles which may be vectored downwardly to provide a component of vertical lift. The market for V/STOL combat aircraft is relatively small and the high cost associated with design,testing and production of a new aircraft means that, in practice, some developments are based on existing designs.
Several attempts have been made to design a vertical landing variant of a conventional landing combat aircraft such as the European Fighter Aircraft (EFA) but the result has usually been that the internal vertical lift modifications required ripple through the aircraft, leaving little of the original, and thus requiring major redesign.
Accordingly a need exists for a V/STOL configuration aircraft which requires less modification of the internal structure which allows a conventional landing combat aircraft to be configured for V/STOL operation, either during original manufacture, or a refit, or as required.
In one aspect, this invention provides an aircraft having a powerplant with an aft-directed main propulsion outlet means for providing forward thrust, and further including duct means having an inlet for receiving at least a proportion of the efflux from said main propulsion outlet means and extending forwardly to an auxiliary outlet disposed adjacent or forwardly of the centre of gravity of the aircraft, said auxiliary outlet being arranged to exhaust efflux with at least a vertical component.
By this arrangement, a proportion of the efflux from the main powerplant is collected from the main propulsion outlet and conveyed forwardly to exhaust with a downward component, thereby generating lift.
Preferably, said auxiliary nozzle is vectorable to vector the thrust generated by said outlet.
The duct means is preferably disposed generally externally of the main body of the aircraft. Preferably at least part of the duct means is moveable to a low drag stowed configuration for normal flight. Thus the end portions of the duct, which turn the efflux through a substantial angle, may be stowed to a low profile configuration. In one arrangement, the remainder of the duct may be left open-ended to provide low drag. In another configuration, the whole duct may be made collapsible so that it may be collapsed or concertina-ed to a low profile position adjacent the aircraft body.
Where the aircraft powerplant has two or more aft-directed propulsion outlets, the duct means conveniently has an inlet having respective inlet aperture regions facing or engaging with the associated propulsion outlets.
The auxiliary propulsion outlet may take many forms. In one arrangement, the auxiliary propulsion outlet may be disposed adjacent the centre gravity of the aircraft, exhausting substantially all of the efflux received from the aircraft powerplant. Alternatively, the auxiliary propulsion outlet may be disposed forwardly of the centre of gravity of the aircraft, with the duct including a further auxiliary outlet means disposed rearwardly of the centre of gravity. The dimensions and location of the outlets are preferably selected such that any resultant pitching moment applied thereby is nil or relatively low. In another development of this arrangement, the further auxiliary outlet may be disposed forwardly beyond the aircraft nose. In this case, the further auxiliary outlet may be provided in the end of a portion which is telescopically moveable with respect to the remainder of the duct means.
The aircraft preferably also includes reaction control means for trim and control during hovering, which advantageously comprise, reaction control nozzles, at least some of which receive and exhaust a portion of the efflux in said duct means.
Whilst the invention has been described above, it extends to any inventive concept set out above or in the following description.